A microwave communication package may include an electronic circuit on a substrate and an antenna for microwave communication with external devices. Within the package, a microwave communication conduit is required between the electronic circuit and the antenna. In the prior art, the substrate and antenna have been mounted on opposite sides of a base plate, with the electronic circuit on the side of the substrate opposite the base plate. To provide a conduit for microwave communication within the package between the electronic circuit and the antenna, waveguides have been constructed through the substrate in line and coupled with waveguides through the base plate. This arrangement has the undesirable consequences of requiring construction of a waveguide through the solid dielectric material of the substrate and further requiring the microwave signal to propagate through the dielectric material of the substrate waveguide to a base plate waveguide of dissimilar physical size, resulting in mismatch losses.